OK, according to the Federal-Mogul master engine bearing specification manual:
Main bearings 1-3: oil clearance .0005"-.0033"
Main bearing #4: oil clearance .0013-.0043
Rod bearings: .0007"-.0032"
To get an accurate idea of main bearing clearance with the engine in the vehicle, use a small hydraulic jack placed on an appropriate amount of support like blocks of wood to put a slight amount of upward pressure on the crankshaft near the main bearing you're checking. This pushes the crank toward the upper bearing shell. (If the engine is upside down on an assembly stand, don't worry about counterbalancing the weight of the crankshaft.) Wipe the crankshaft surface and the bearing in the cap clean of oil and torque the cap to specification, then remove the cap and measure the width of the flattened Plastigauge. A small squirt of penetrating oil helps to remove the flattened PG, but if a small residue remains, it's designed to dissolve as soon as it's exposed to motor oil. Continue with the support procedure and clearance checking until all the bearings are checked. On the rods, just wipe the crank surface and the bearings clean and check the clearance- - - -the weight of the piston/rod assembly is negligible. I like to see clearances somewhere in the .0015" range, + or - a little. More clearance = less oil pressure. The green PG should be in the right clearance range for unworn bearings. Red is another option if you're measuring bearings with a little wear on them.
Jerry
